Jim Crow laws, which were a system of laws meant to discriminate against African Americans, spread across the U.S.
Plessy v. Ferguson allowed 'separate but equal,' also known as segregation, to become law in the United States.
They are complete and polar opposites. Jim Crow Laws were suppose to be made TO discriminate against African Americans. Plessy v. Ferguson was to tell the U.S. that African Americans are separated, but should be treated as equals.